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D C Parish

Publications and source records attributed to D C Parish.

At least 37 records · Page 2Linked to original sources
PubMed1994

Characterization of a metalloprotease from ovine chromaffin granules which cleaves a proenkephalin fragment (BAM12P) at a single arginine residue.

A metalloprotease has been identified in ovine chromaffin granules which cleaves the proenkephalin fragment BAM12P to produce adrenorphin-Gly. This cleavage occurs at a single arginine residue and is an intermediate step in the production of the opiate adrenorphin in vivo. The identity of the product was confirmed by reverse-phase and ion-exchange chromatography. The adrenorphin-Gly-generating enzyme (AGE) was determined by chromatofocusing to have a pI value of 5.2 and bound strongly to a metal-chelate affinity column. After purification by gel-filtration and ion-exchange chromatography AGE was free of contaminating activities, as cleavage of radiolabelled BAM12P generated a single product as judged by reverse-phase and ion-exchange chromatography. The enzyme has a molecular mass of approx. 45 kDa and a pH optimum of 8.6 in Mops, Taps and Hepes buffers, but was inhibited by phosphate buffers. It was inhibited by micromolar concentrations of copper and zinc ions, but not by millimolar concentrations of calcium or manganese ions. The addition of BAM22P, dynorphin 1-13 or dynorphin 1-8 to the incubation mixture inhibited the cleavage of radiolabelled BAM12P. The cleavage was also inhibited by the presence of catecholamines at concentrations similar to those found within the chromaffin granule. This may explain the known effect of reserpine on chromaffin cells of reducing catecholamine levels and simultaneously increasing adrenorphin levels. It may also indicate a function for AGE and adrenorphin as reporters of intragranular conditions.

Adrenal Medulla↗
PubMed1994

Separation of ovine chromaffin granules from lysosomes by successive isoosmolar and hyperosmolar density gradient centrifugation.

Preparations containing ovine chromaffin granules and lysosomes were obtained by differential centrifugation and applied to density gradients. In isoosmolar linear Metrizamide gradients the granules had a lower density than the major portion of the lysosomes (1.05 compared to 1.15); however, in hyperosmolar linear Metrizamide gradients the granule density increased and they migrated close to the lysosomes. The granules separated into two bands on a discontinuous isoosmolar Metrizamide gradient; however, these two bands were similar in terms of granule and lysosomal markers. On a discontinuous hyperosmolar sucrose gradient the granules were more dense than the lysosomes, the reverse of the situation on the Metrizamide gradient. Separation on a discontinuous isoosmolar Metrizamide gradient followed by a 1.8 M sucrose cushion provided a 54-fold purification of granules from lysosomes and similar separations from other subcellular markers. This procedure also provided a 37-fold purification of bovine granules from lysosomes. It was demonstrated that thimet oligopeptidase (EC 3.4.24.15) occurred in the adrenal medulla but is not principally located in the chromaffin granule.

Adrenal Medulla↗
PubMed1994

Functional morphology of the light yellow cell and yellow cell (sodium influx-stimulating peptide) neuroendocrine systems of the pond snail Lymnaea stagnalis.

Neuroendocrine light yellow cells of the pond snail Lymnaea stagnalis express a neuropeptide gene encoding three different peptides. The morphology of the cell system has been studied by in situ hybridization, using two synthetic oligonucleotides encoding parts of light yellow cell peptides I and III, and by immunocytochemistry with antisera to synthetic light yellow cell peptide II and to two fragments of light yellow cell peptide I. One large cluster of light yellow cells was observed in the ventro-lateral protrusion of the right parietal ganglion, smaller clusters lying in the posterior dorsal part of this ganglion and in the visceral ganglion. The cells had an extended central neurohaemal area. Immunopositive axons projected into all nerves of the ganglia of the visceral complex, into the superior cervical and the nuchal nerves, and into the connective tissue surrounding the central nervous system. Axon tracts ramified between the muscle cells of the walls of the anterior aorta and of smaller blood vessels. Peripheral innervation by the light yellow cell system was only found in muscular tissue of the ureter papilla. The antisera to the two peptide fragments of light yellow cell peptide I not only stained the light yellow cells, but also the identified yellow cells, which have previously been shown to produce the sodium influx-stimulating neuropeptide. The latter cells were negative to the in situ hybridization probes and antisera specific to the light yellow cell system. It is therefore unlikely that the yellow cells express the light yellow cell neuropeptide gene. Nevertheless, the cells contain a neuropeptide sharing antigenic determinants with light yellow cell peptide I.(ABSTRACT TRUNCATED AT 250 WORDS)

Amino Acid Sequence↗
PubMed1994

Arteriographic incidence of coronary artery disease in black men with chest pain.

To determine the incidence of arteriographically proven coronary artery disease in black men evaluated for chest pain, we retrospectively reviewed the charts of 208 black men, aged 20 to 60, who had coronary arteriography at the Medical Center of Central Georgia (MCCG) from 1985 through January 1990. Age, type of chest pain, and risk factors commonly accepted as associated with coronary disease (hypertension, family history, left ventricular hypertrophy, diabetes, smoking, and hypercholesterolemia) were identified for each patient. Patients were categorized by previous evidence of coronary disease: 145 were studied to evaluate suspected disease and 63 to evaluate previously proven (prior catheterization) or presumptive (prior myocardial infarction) disease. Chest pain groups (typical and atypical angina) were analyzed by Pearson chi-square goodness of fit using the Diamond and Forrester age and chest pain tables as a model. Risk factors were analyzed using a maximum likelihood chi-square test. Coronary artery disease was common in the study group (48.6% of all patients) but significantly less than predicted by the Diamond and Forrester tables. Risk factors were highly prevalent, but only age and smoking were associated with catheterization-proven coronary artery disease in this group. We conclude that coronary artery disease is common in black men evaluated for chest pain but less frequent than would be expected from comparison with findings in white men presenting similar clinical features. Risk factors other than age and smoking were not associated with increased incidence of disease. A prospective study is needed to delineate a more effective means of evaluating black male patients with chest pain.

Adult↗
PubMed1993

A cholinergic modulatory interneuron in the feeding system of the snail, Lymnaea.

1. Pharmacological and physiological methods were used to examine the role of acetylcholine (ACh) in modulation of the Lymnaea feeding central pattern generator (CPG) by the slow oscillator (SO) interneuron. 2. Extracts of dissected SO cell bodies inhibited spontaneous ventricular contractions of the clam Mya arenaria, indicating the presence of ACh. These effects were blocked by the specific antagonist benzoquinonium chloride (10(-7) M). 3. Isolated SO cells grown in culture synthesized ACh from tritiated choline. 4. High [K+] saline induced release of synthesized ACh from cultured SO cells into the medium. 5. The specific ACh antagonist phenyltrimethylammonium (10(-4) M) blocked both excitatory, biphasic (inhibitory-excitatory) and inhibitory monosynaptic connections from the SO to feeding CPG interneurons and motor neurons. Less specific cholinergic antagonists blocked either excitatory (hexamethonium, 10(-4) M) or both excitatory and inhibitory connections (d-tubo-curarine, 10(-4) M). 6. The synaptic responses of the SO could be mimicked by brief (20 ms) pressure-pulsed application of ACh onto the cell bodies of the postsynaptic cells in high-Mg2+ saline. In normal saline, ACh elicited bursts of spikes in the N1 cells, indicating that a fictive feeding pattern had been induced in the CPG. This mimics the main mechanism by which the SO activates the CPG, which is by exciting the N1s. 7. The frequency of SO-induced fictive feeding rhythm was reduced by bath application of hexamethonium chloride to the buccal ganglia. This reduced the amplitude of the SO-->N1 excitatory synaptic response (30% of controls) and is probably the main mechanism for the reduction in the frequency of the rhythm. 8. The evidence suggests that ACh is the main neurochemical involved in allowing the SO to initiate and control the frequency of the Lymnaea feeding CPG.

Acetylcholine↗
PubMed1991

Immunogenicity of low-dose intradermal recombinant DNA hepatitis B vaccine.

Low-dose intradermal vaccination with plasma-derived hepatitis B vaccine has been shown to give high rates of seroconversion at greatly reduced vaccine cost. We report a study comparing two groups given lower doses (1.0 or 1.5 microgram) of recombinant-derived vaccine intradermally with a control group given the standard intramuscular dose. Of the 132 randomized medical students and hospital employees, 95 completed the study. Rates of seroconversion and peak antibody titers were comparable, though antibody rose more slowly and fell somewhat faster in the intradermal groups. Increasing the intradermal dose did not improve response. Most intradermal vaccinees (80%) developed small (average 2 to 3 mm) areas of local induration, which faded slowly. Low-dose intradermal vaccination with recombinant hepatitis B vaccine results in high rates of seroconversion (greater than 90% in each protocol) at a cost that will allow individual practitioners and program with limited budgets to offer vaccination.

Adult↗
PubMed1990

Sudden death in rheumatoid arthritis from vertical subluxation of the odontoid process.

Rheumatoid arthritis is a chronic, multisystem disease that causes significant morbidity and early mortality. A common source of morbidity in severe rheumatoid arthritis is involvement of the cervical spine. Sudden death due to subluxation of the odontoid process into the medulla oblongata is a dramatic but rare complication. We report the case of a patient who died suddenly. Computerized tomography scan, autopsy, and clinical findings were correlated. Studies of cervical involvement in rheumatoid arthritis were analyzed for cases of vertical subluxation. The case reports of sudden deaths and patients treated for vertical subluxation were reviewed; they revealed a trend toward surgery in patients with neurological abnormalities. However, a comparison of clinical outcome does not demonstrate improved survival with surgical intervention. Randomized trials comparing surgical with nonsurgical therapy are needed.

Aged↗
PubMed1989

Characterisation and partial purification of a novel prohormone processing enzyme from ovine adrenal medulla.

An enzymatic activity has been identified which is capable of generating a product chromatographically identical with adrenorphin from the model substrate BAM12P. This enzyme was purified by gel filtration and ion-exchange chromatography and characterised as having a molecular mass between 30 and 45 kDa and an acidic pI. The enzyme is active at the acid pH expected in the secretory vesicle interior and is inhibited by EDTA, suggesting that it is a metalloprotease. This activity could not be mimicked by incubation with lysosomal fractions and it meets the criteria to be considered as a possible prohormone processing enzyme.

Adrenal Medulla↗
PubMed1989

Problem-based ACLS instruction: a model approach for undergraduate emergency medical education.

The optimal format for teaching advanced cardiac life support (ACLS) to medical students and other groups with little emergency medicine experience has not been studied extensively. We report an ACLS provider course that was taught to sophomore medical students using a self-directed, problem-based learning model. The traditional two-day provider course format was replaced by a series of clinical problems that emphasized various aspects of the ACLS curriculum. Students then met weekly with an ACLS instructor who served as a tutor to discuss the problem. A specific set of learning objectives for the entire ACLS curriculum was developed into a study unit index and given to students at the beginning of the course. Enhanced practice time was offered to students in the form of traditional teaching stations and skills laboratories. Students were tested using standard ACLS criteria. The students in the problem-based course achieved a higher pass rate on the written test and skills stations than senior medical students did in a standard two-day course during the same time period. The problem-based format with enhanced practice time would appear to be an effective alternative for groups that need to acquire the basic skills needed in a resuscitation attempt but have little previous experience in this area.

Curriculum↗
PubMed1986

Purification and characterization of a paired basic residue-specific prohormone-converting enzyme from bovine pituitary neural lobe secretory vesicles.

The neuropeptides arginine vasopressin and oxytocin are generated from their prohormones in the hypothalamoneurohypophysial system by enzymatic cleavages at paired basic residues (i.e. Lys-Arg). This study describes the purification of an enzyme from bovine neural lobe secretory vesicles, the putative site of this processing, which is capable of cleaving several prohormones at paired basic residues. The enzyme is a glycoprotein of Mr approximately 70,000 and has an acidic pH maximum. It processes the heterologous precursors pro-opiomelanocortin and insulin at paired basic residues in a manner similar to a pro-opiomelanocortin-converting enzyme derived from bovine intermediate lobe secretory vesicles which has been described previously. In addition, the neural lobe-derived converting enzyme cleaves the human vasopressin prohormone in vitro to yield arginine vasopressin-Gly10-Lys11-Arg12 as the major vasopressin cleavage product. This indicates that the enzymatic cleavage in the vasopressin precursor occurred primarily on the carboxyl side of the arginine in the pair of Lys-Arg basic residues separating the vasopressin peptide from the neurophysin moiety in the precursor. The properties of the neural and intermediate lobe-derived enzymes are virtually identical, raising the possibility that a family of similar enzymes may be responsible for cleaving a number of prohormones at paired basic residues in different tissues.

Animals↗
PubMed1985

Regulation of pro-opiomelanocortin synthesis by dopamine and cAMP in the amphibian pituitary intermediate lobe.

The modulation of pro-opiomelanocortin (POMC) synthesis in Xenopus laevis pituitary intermediate lobe (IL) during background adaptation and the role of dopamine and cAMP in mediating this effect were examined. Neurointermediate lobes (NILs) were pulselabeled in vitro with [3H]arginine and analyzed for POMC synthesis by acid-urea gel electrophoresis. After black background adaptation of the animal (7 days), POMC synthesis increased 5-6-fold, while after white background adaptation (7 days), POMC synthesis decreased by 76%. Dopamine (50 microM) suppressed POMC synthesis in NILs in culture. In the absence of dopamine, POMC synthesis was stimulated. Several experiments were conducted to determine the category of dopamine receptor in the X. laevis IL. A D-2 dopamine receptor agonist inhibited immunoreactive alpha-MSH release from the NIL in a D-2 antagonist-reversible manner. A D-1 receptor agonist or antagonist did not alter the release of immunoreactive alpha-MSH from the NIL. Dopamine (10 microM) inhibited forskolin-stimulated cAMP accumulation. In addition, dopamine inhibition of POMC synthesis in cultured ILs was reversed by 8-Br-cAMP. These studies suggest that white background adaptation results in stimulation of the X. laevis D-2 receptor, which reduces cAMP production and POMC synthesis. Conversely, during black background adaptation the IL D-2 receptor is not stimulated, leading to increased cAMP production and POMC synthesis.

8-Bromo Cyclic Adenosine Monophosphate↗
PubMed1985

Purification and characterization of a paired basic residue-specific pro-opiomelanocortin converting enzyme from bovine pituitary intermediate lobe secretory vesicles.

Pro-opiomelanocortin (adrenocorticotropin/endorphin prohormone) is processed to yield active hormones by cleavages at paired basic amino acid residues. In this study, an enzyme that specifically cleaves at the paired basic residues of this prohormone has been purified from bovine pituitary intermediate lobe secretory vesicles, the intracellular processing site of proopiomelanocortin. This enzyme, named pro-opiomelanocortin converting enzyme, has been characterized as a glycoprotein of Mr approximately 70,000. It has an apparent isoelectric point between 3.5 and 4.0. The pH optimum of the pro-opiomelanocortin converting enzyme is between 4 and 5, but the enzyme is highly active at the intravesicular pH of 5.1-5.6. The enzyme specifically cleaved the Lys-Arg pairs of pro-opiomelanocortin to yield Mr = to 21,000-23,000 ACTH, beta-lipotropin, Mr 13,000 and 4,500 ACTH, beta-endorphin, and a Mr = 16,000 NH2-terminal glycopeptide, the products synthesized by the pituitary intermediate lobe in situ. NH2- and COOH-terminal analysis of the products indicated that the pro-opiomelanocortin converting enzyme cleaves the peptide bond either between the Lys and Arg or on the carboxyl side of the Arg at Lys-Arg pairs of pro-opiomelanocortin. The intracellular localization, pH optimum, and cleavage specificity of the enzyme suggest that it may function as a pro-opiomelanocortin processing enzyme in the pituitary intermediate lobe in vivo.

Amino Acid Sequence↗
PubMed1983

The C-terminal dipeptide of beta-endorphin: a neuropeptide with inhibitory activity.

Glycylglutamine, the C-terminal dipeptide of beta-endorphin, has previously been shown to be present in porcine pituitary. Evidence is given that this dipeptide occurs in ovine brain stem where its concentration was shown to be similar to that of the complementary fragments of beta-endorphin determined by chromatography and radioimmunoassay. Using the technique of microiontophoresis an inhibitory activity of the dipeptide was demonstrated on neurones located in the reticular formation of rat brain stem.

Animals↗
PubMed1981

Effects of small doses of colchicine on the components of the hypothalamo-neurohypophysial system of the rat.

Small doses (3.5 micrograms and 7 micrograms) of colchicine injected intracisternally caused an interruption of transport of secretory material from the supraoptic and paraventricular nuclei of the hypothalamus to the neural lobe of the pituitary gland. Transport was assessed by direct measurement of the incorporation of [35S] cysteine into neurophysins, by radioimmunoassay of accumulated material in discrete areas of the system and by immunocytochemistry. The larger dose (7 micrograms) switched off transport completely during the first 24h but the system began to recover within three to four days. Colchicine had little, if any, effect on synthesis; comparison of the relationships of the apparent amounts of immunoreactive neurophysins and immunoreactive hormones in the arrested product led to the conclusion that processing of the hormone precursors continues within secretory granules which accumulated in the perikarya.

Animals↗
PubMedDate not supplied

Relation of the pre-employment drug testing result to employment status: a one-year follow-up.

All employees hired over a six-month period at a large hospital underwent pre-employment urinary toxicology screening. Results of the screening were kept confidential. After a year of employment, the personnel folders of all employees studied were reviewed. Twenty-two of 180 employees (12%) had tested positive for drug use. Employees in clerical/aide positions were significantly more likely to test positive than were employees in professional positions (17% vs. 6%). Drug-positive employees were also more likely to be young and male. Comparison of job performance variables, job retention, supervisor evaluations, and reasons for termination showed no difference between drug-positive and drug-negative employees. Eleven drug-negative employees were fired during the study; no drug-positive employee was fired. There was a strongly significant difference between clerical and professional employees on each of these variables. This study did not find a relation between drug use and job performance. The widespread use of drug screening prior to employment makes further studies of this issue important.

Adult↗